Electrical switching device using constricted fluid conducting path



Jan. 21, 1969 R. BRANDER 3,423,704 ELECTRICAL SWITCHING DEVICE USINGCONSTRICTED FLUID CONDUCTING PATH Filed Oct. 31, 1966 I ,1 20 l lR/CHARD BRANDER BY v i h M) ATTORNEYS United States Patent ELECTRICALSWITCHING DEVICE USING CON- STRICTED FLUID CONDUCTING PATH RichardBrander, Chicago, Ill., assignor to Beltone Electronics Corporation, acorporation of Illinois Filed Oct. 31, 1966, Ser. No. 590,988

US. Cl. 33547 8 Claims Int. Cl. H01h 29/00 ABSTRACT OF THE DISCLOSURE Aswitch comprising a rigid non-conducting envelope having a plurality ofspaced-apart electrical terminals extending through its walls and anelectrically conductive, non-wetting fluid partially filling itsinterior and in contact with said terminals. A rigid, electricallyinsulated actuating member is pivotally mounted within the envelope suchthat in one position a passage is provided for the fluid to form anelectrically conductive path between the terminals and in anotherposition the passage is constricted between the actuating member and theenvelope to separate the fluid in non-contacting segments to break theelectrically conductive path between the terminals.

This invention relates to an electrical switching arrangement whereinelectrical connections are established through electrical conductivenon-wetting fluids such as mercury.

US. Patent No. 3,177,327, which issued to Erwin M. Weiss on Apr. 6,1965, discloses a fluid switch construction employing a sealed,deformable container partially filled with an electrically conductive,non-wetting fluid. When the vessel is deformed to constrict afluid-holding passage between the terminals of the switch, the fluidphysically separates to open the electrical circuit path.

The operation of the Weiss invention is based upon the interactionbetween surface tension forces and internal pressure forces within thedeformable container and possesses numerous significant advantages.Undesirable contact openings and closures due to contact bounce(resulting from the elastic collision which takes place between thecontacts in a mechanical switching device) are eliminated. Furthermore,the sealed fluid switch described in the above patent does not sufferfrom the effects of contact deterioration or the formation ofcontaminating films between the contacts. Moreover, the usual necessityfor supplying substantial contact pressure in order to minimize contactresistance is eliminated.

Through extended use, the deformable portions of these prior fluidswitches are subject to wear. In addition, a substantial portion of theenergy which is required to actuate such a switch is consumed by thedeformation of the vessel rather than by the actual separation of themercury. Also in many applications it is desirable to have a switchwhich is hermetically sealed to prevent the passage of gaseouscontaminants.

It is accordingly an object of the present invention to provide a fluidswitch having the above numerated advantages but which does not requirethe deformation of the fluid container.

It is a further object of the invention to provide a fluid switch whichrequires the application of very little actuating energy in order toaccomplish switching.

It is a further object of this invention to provide a fluid switch whichcan be operated in any position and which can be hermetically sealedagainst environmental contamination.

It is a still further object of the invention to provide a highlyreliable fluid switch of exceedingly simple con- 3,423,704 Patented Jan.21, 1969 ICC struction which is substantially free from the contactbounce effect.

In a principle aspect, the present invention takes the form of a fluidswitch which includes a pair of electrically conductive contactterminals which are spaced apart within a passage defined by a hollow,rigid, electrically insulated envelope. According to a feature of theinvention, a rigid, electrically insulated, actuating member is movablymounted within the passage and the passage is at least partially filledwith an electrically conductive, non-wetting fluid. As contemplated bythe invention, means are employed for moving the actuating member toconstrict a portion of the passage such that the fluid separates intonon-contacting physical segments thereby breaking the electricallyconductive path through the fluid between the terminals.

In a preferred embodiment of the invention, the actuating member isconstructed of magnetic material which may be coated with insulation andwhich is mounted within the passage for pivotal movement. An appliedmagnetic field may then be employed to accomplished switching.

These and other objects, features and advantages of the invention willbecome more apparent through a consideration of the following detaileddescription. In the course of this description, reference willfrequently be made to the attached drawings in which:

FIGURE 1 is a top plan view of a single-pole, doublethrow switchcartridge embodying the principles of the invention;

FIGURE 2 is a side cross-sectional view of the switch cartridge takensubstantially along the line 2-2 of FIG- URE l and showing an externallymounted, movable permanent magnet for actuating the switch cartridge;and

FIGURE 3 shows a side cross-sectional view of a second switch cartridgewhich embodies the principles of the invention and which is actuated byan associated electromagnet.

The top view of a switch cartridge employing the principles of theinvention is shown in FIGURE 1. The cartridge includes a rigid envelopeindicated generally at 11, three electrical conductors 13, 15 and 17which pass through the container, and a movable actuating memberindicated generally at 19. The actuating member 19 includes indentations18 and 20 at its ends.

As most clearly seen in FIGURE 2, the floor of the vessel 11 is providedwith a pair of raised ribs 21 and 22 which extend into the interiorhollow portion of the container 11 from the floor 23 of container 11.The conductors 13, 15 and 17 are in the shape of strips and rest againstthe floor 23 of the container 11. With actuating member 19 in theposition shown in FIGURE 2, the strips 13 and 15 are electricallyconnected through the non-wetting electrically conductive fluid segment25A. The strip 17 is in electrical contact with the fluid segment 25B.Fluid segments 25A and 25B partially fill the container 11. Theremainder of the interior hollow portion of the container 11 (forexample the region shown at 28) may be evacuated, gas-filled, or filledwith a non-conductive liquid which is not miscible with mercury. Thecontainer 11 may be hermetically sealed to protect against atmosphericcontamination.

The actuating member 19, which is coated with an insulating filmindicated generally at 29, serves to make and break connections throughthe fluid 25. The member 19 conforms closely to each of the four sidewalls of the container 11 except for the passages provided byindentations 18 and 20 as shown in FIGURE 1. Surface tension forcesprevent the passage of the fluid 25 through the narrow gaps betweenmember 19 and the inner walls of container 11 except at the passagesprovided by indentations 3 18 and 20. As seen in FIGURE 2, the bottomsurface 30 of the actuating member 19 is substantially flat while thetop surface comprises two bevelled surfaces 31 and 32, the planes ofwhich are at an angle to one another and which intersect along thefulcrum line 33.

The switch cartridge shown in FIGURE 2 is actuated by a pivotallymounted permanent magnet shown generally at 35 which rotates aboutfulcrum wire 38. In the position shown, the permanent magnet 35 has beenrotated in a counterclockwise fashion about the fulcrum wire 38 to placethe left-hand pole piece 39 in a position closely adjacent to theleft-hand end 40 of the actuating member 19, causing the member 19 topivotally rotate about the fulcrum line 33 such that bevelled surface 31is flush against the inner surface of the roof 42 of the vessel 11. Inthis position, the bottom surface 30 of member 19 is spaced apart fromthe rib 21 to open a passage between the conductors 13 and 15. Sincethis passage is filled with mercury segment 25A, a current carrying pathis provided between conductors 13 and as illustrated by the dotted line50. The rib 22 is in a position of engagement (or near engagement) withthe bottom surface 30 of the actuating member 19 causing the mercury toseparate into the spaced apart physical segments A and 25B. Accordingly,the circuit path which might otherwise exist between conductors 15 and17 is broken.

Downward movement of the right hand pole member 55 of magnet 35 causesthe actuating member 19 to pivot in a counterclockwise fashion aboutfulcrum line 33 such that bevelled surface 32 is moved to a position ofengagement with the inner surface 42 of the vessel 11. In this position,as will be readily understood, the fluid passage connecting conductors13 and 15 is constricted to separate the mercury and a fluid path iscreated between conductors 15 and 17. It thus may be seen that anarrangement shown in FIGURES 1 and 2 constitutes a single pole, doublethrow, fluid switch.

The magnetic actuating member 19 need not be securely fixed at any pointto the container 11, the magnetic attraction from the movable magnet 35and the floating action contributed by the mercury segments 25A and 25Bbeing sufficient to hold the actuating element in an upward position. Ifdesired, of course, the actuating element 19 could be supported by atransverse fulcrum pin which engages with both the side walls of thecontainer 11 and the magnetic actuating member 19.

FIGURE 3 of the drawings shows a further embodiment of the invention inwhich projecting ribs 60 and 61 are included along the bottom surface 63of an actuating member shown generally at 67. As before, the uppersurface of the actuating member 67 is composed of two bevelled walls 31and 32 lying in planes at an angle to one another which intersect alonga fulcrum line 33. Other portions of the arrangement shown in FIGURE 3which are identical in placement and function to like elements in thecartridge shown in FIGURES 1 and 2 have been designated by the samenumbers used earlier.

The switching arrangement shown in FIGURE 3 is actuated by a pair ofmagnetizing windings 70 and 71. The magnetizing winding 70 is wound on acore 72 and is connected in series with a switch 74 across the terminalsof the battery 75 while the winding 51, which is also wound on core 72,is connected in a series of a switch 78 across terminals of a battery80. A permanent magnet 82 is positioned between windings 70 and 71against core 72. When the switch 74 is closed, current flowing in thewinding 70 induces a strong magnetic field within the left hand side ofcore member 72 causing the actuating member 67 to rotate pivotally aboutthe fulcrum line 33 to the position shown in FIGURE 3. In this position,a passage filled with the conductive fluid segment 25A exists betweenconductors 13 and 15, electrically connecting these conductors. The ri-bmember 61 constricts the passage between conductors 16 and 17,separating the mercury fluid into the two physically separated segments25A and 25B as shown thereby breaking the circuit connection betweenconductors 15 and 17.

When the switch 74 is opened, removing the applied magnetic field, theweaker magnetic field contributed by the permanent magnet 82 holds theactuating member 67 in the position shown. Thus, the arrangement ofFIGURE 3 operates as a pulse operated latching switch which may bepulsed to cause switching but which does not require continuedenergization to maintain a switched condition.

It is to be understood that the embodiments of the invention which havebeen described are merely illustrative of applications of principles ofthe invention. Numerous modifications maye be made by those skilled inthe art without departing from the true spirit and scope of theinvention.

What is claimed is:

1. An electrical switch comprising, in combination, a rigid,non-conducting, sealed envelope, a pair of spacedapart, electricallyconductive contact terminals passing through the walls of said envelope,an electrically conductive, non-wetting fluid partially filling theinterior of said sealed envelope and electrically contacting saidcontact terminals, a rigid, electrically insulated actuating membercompletely enclosed within said sealed envelope, said actuating memberbeing pivotally mounted for movement into either one of two positionswithin said envelope such that in one position a passage is formed inwhich the fluid forms an electrically conductive path between saidcontact terminals, and such that in another position the passage isconstricted between the actuating member and a portion of said envelopeto cause the fluid to separate into non-contacting physical segments tobreak the electrically conductive path, and means located outside ofsaid sealed envelope and mechanically independent of said actuatingmember for causing said actuating member to be pivotally moved withinsaid envelope between two said positions.

2. An electrical fluid switch as set forth in claim 1 wherein saidactuating member is composed at least partially of magnetic material andwherein said means for moving said actuating member comprise means forsubjecting said actuating member to a magnetic field.

3. A combination as set forth in claim 1 including a raised ribprojecting from one interior wall of said envelope and positioned forcooperation with said movable actuating member to constrict saidpassage.

4. A fluid switch as set forth in claim 1 including a raised ribprojecting from said actuating member and positioned for cooperationwith an interior wall of said envelope to constrict said passage.

5. An electrical fluid switch as set forth in claim 2 wherein said meansfor subjecting said actuating member to a magnetic field comprises anelectro-magnet positioned outside said envelope.

6. A single-pole, double throw switch comprising in combination, arigid, non-conducting sealed envelope, first, second, and thirdspaced-apart electrically conductive contact terminals passing throughthe walls of said envelope, an electrically conductive, non wettingfluid partially filling the interior of said sealed envelope andelectrically contacting said contact terminals, a rigid, electricallyinsulated actuating member completely enclosed within said sealedenvelope, said actuating member being pivotally mounted for movementinto either one of two positions within said envelope such that in oneposition a passage from the first contact terminal to the second contactterminal is constricted between the actuating member and a portion ofthe envelope to cause the fluid to separate into non-contacting physicalsegments for breaking the electrical conductive path therebetween whilean electrical conductive path exists between the second and thirdcontact terminals, and in a second position a passage from the secondcontact terminal to the third contact terminal is so constricted forbreaking the electrical conductive path therebetween while an electricalconductive path exists between the first and second contact terminals,and means located outside of said sealed envelope and mechanicallyindependent of said actuating member for causing said actuating memberto be pivotally moved within said envelope between the two saidpositions.

7. An arrangement as set forth in claim 6 wherein said actuating memberis at least partially composed of magnetic material and wherein saidmeans for moving said actuating member comprises means for subjectingsaid member to a magnetic field.

8. An arrangement as set forth in claim 7 wherein said means forsubjecting said member to a magnetic field comprises first and secondelectromagnets, said first electromagnet being positioned to pivot saidmember in a first sense when energized and said second electromagnetbeing positioned to pivot said member in the opposite sense whenenergized.

References Cited UNITED STATES PATENTS 2,750,466 6/1956 Patterson200152.9 3,142,736 7/1964 Mitchell 335-52 3,198,911 8/1965 Mitchell335-52 BERNARD A. GILHEANY, Primary Examiner.

HAROLD BROOME, Assistant Examiner.

US. Cl. X.R. 200-152

